An image forming apparatus such as a copying machine or a printer includes a fuser in which a fixing belt having a small heat capacity is used to save consumed energy of a heating source and realize a quick rise in temperature of the fixing belt. In a fixing belt that rotates with both ends thereof supported by flanges, tension in the circumferential direction is not applied to an intermediate region in a rotation axis direction of the fixing belt. Therefore, there is a fuser in which pressing member is arranged on the inner side of the fixing belt and the fixing belt is held between the pressing member and a pressurizing roller to form a nip.
In the fuser that forms the nip using the pressing member, if a friction force of the fixing belt and the pressing member is large, a load applied to the fixing belt increases. Therefore, it is necessary to increase rotation torque necessary for the rotation of the fixing belt. If the friction force of the fixing belt and the pressing member is large, it is likely that the fixing belt is worn down and deterioration of the fixing belt is accelerated.